The etiology of tinnitus can be divided into tinnitus originating from within the auditory system (also called subjective tinnitus) and tinnitus originating from outside the auditory system (objective tinnitus). Some authors divide it into two kinds as follows:
A) Tinnitus originating from within the auditory system
Subjective tinnitus is tinnitus only the patient can hear. This is the most common type of tinnitus. It is due to a sensorineural hearing loss which results from a dysfunction within the auditory system. It can be caused by a problem within the peripheral auditory system (the outer, middle or inner ear) or within the central auditory system (the auditory nerves or the part of your brain that interprets nerve signals as sound i.e. auditory pathways).
The causes of tinnitus originating from within the auditory system are many and are listed in the differential diagnosis of tinnitus.
B) Tinnitus originating from outside the auditory system
Objective tinnitus is tinnitus the provider can hear when he or she does an examination. This rare type of tinnitus may be caused by a blood vessel problem, a middle ear bone condition or muscle contractions.”
Causes of tinnitus originating from outside the auditory system
Vascular disorders (Pulsatile tinnitus)
Arterial bruits (from atherosclerosis): With age, atherosclerosis leads to narrowing and loss of some elasticity–the ability to flex or expand slightly with each heartbeat. That causes blood flow to become more forceful (turbulent), making it easier for your ear to detect the beats. A patient can generally hear this type of tinnitus in both ears.
Arteriovenous Malformations. Congenital AVMs may be associated with hearing loss or tinnitus. This type of tinnitus generally occurs in only one ear.
Paraganglioma. Head and neck paragangliomas are highly vascular but usually benign neoplasms. They commonly cause a loud pulsing tinnitus that may interfere with hearing.
Head and neck tumors. A tumor that presses on blood vessels in your head or neck (vascular neoplasm) can cause tinnitus and other symptoms.
Hypertension (systemic or intracranial) produces venous hums. Systemic HTN, increased intracranial pressure (often due to pseudotumor cerebri, etc) can cause venous hums that can cause tinnitus and conductive hearing loss.
Turbulent blood flow. Narrowing or kinking in the carotid artery or jugular vein can cause turbulent, irregular blood flow, leading to tinnitus.
Neurologic disorders: pulsatile tinnitus caused by a muscle spasm one or both of the muscles within the middle ear (the tensor tympani and the stapedius muscle). They are supplied by CN V and VII respectively.
Eustachian tube dysfunction (A patulous eustachian tube)
Temporomandibular joint (TMJ) dysfunction
Whiplash injuries and other cervical-spinal disorders